Asante Samuel to Marcus Williams: 'F**k the Non-Believers!!'

Welcome to "Solid Profanity-Laced Advice for Marcus Williams" .... starring Asante Samuel.

Remember, Samuel dropped a possible Super Bowl winning interception in '08 -- only to bounce back STRONGER the following seasons, leading the NFC in picks in '09 and '10.

So, what pearls of wisdom is he dishing out to New Orleans Saints DB Marcus Williams -- who missed that key tackle on Stefon Diggs on Sunday???

There's a lot of good stuff in this video ... but the best line is this:

"If I was him, my mindset is ... 'That sh*t is over with. F*ck everybody that don't believe in me.'"